In the case of steer-by-wire steering systems, the position of the steered wheels is not directly coupled with the steering wheel. There is a connection between the steering wheel and the steered wheels via electrical signals. The driver's steering command is taken up by a steering angle sensor and, depending on the driver's steering command, the position of the steered wheels is regulated via a steering adjuster. A mechanical connection to the wheels is not provided so that after actuation of the steering wheel, force feedback is missing, for example, a relevant response when parking, where a small force is desired for comfort reasons, or during a usual drive, where a higher steering torque corresponding to the vehicle response is desired. To simulate the feedback of the road on the steering wheel with steer-by-wire steering, it is necessary to provide a feedback actuator on the steering wheel and the steering column, which characterizes a steering feel according to the feedback effects of the steering wheel. This feedback actuator generally consists of an electric motor, which acts on the steering column via a reduction gear. In the case of these steering wheel actuators, it is disadvantageous that their production is associated with high costs and there is a substantial space requirement in the area of the steering column.
DE 195 39 101 C1 discloses a reaction simulation where a restoring torque is exerted on the steering wheel and the steering shaft. Thereby, a return spring arrangement is provided, which exerts a restoring torque on the steering wheel. The desired course of the restoring torque as a function of the steering angle is generated by an electric motor. A disadvantage of this solution is that the motor must be designed with large-scale dimensions accordingly due to the required high level of restoring torques.
Thus a need exists for an improved feedback actuator for a steering mechanism for motor vehicles.